A nuptial pad (also known as thumb pad, or nuptial excrescence) is a

secondary sex characteristic A secondary sex characteristic is a physical characteristic of an organism that is related to or derived from its sex, but not directly part of its reproductive system. In humans, these characteristics typically start to appear during pubert ...

present on some mature male

frog A frog is any member of a diverse and largely semiaquatic group of short-bodied, tailless amphibian vertebrates composing the order (biology), order Anura (coming from the Ancient Greek , literally 'without tail'). Frog species with rough ski ...

s and

salamander Salamanders are a group of amphibians typically characterized by their lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, and the presence of a tail in both larvae and adults. All t ...

s. Triggered by

androgen An androgen (from Greek ''andr-'', the stem of the word meaning ) is any natural or synthetic steroid hormone that regulates the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. This includes ...

hormones, this breeding gland (a type of mucous gland) appears as a spiked

epithelial Epithelium or epithelial tissue is a thin, continuous, protective layer of cells with little extracellular matrix. An example is the epidermis, the outermost layer of the skin. Epithelial ( mesothelial) tissues line the outer surfaces of man ...

swelling on the

forearm The forearm is the region of the upper limb between the elbow and the wrist. The term forearm is used in anatomy to distinguish it from the arm, a word which is used to describe the entire appendage of the upper limb, but which in anatomy, techn ...

and prepollex that aids with grip, which is used primarily by males to grasp (or clasp) females during

amplexus Amplexus (Latin "embrace") is a type of Mating, mating behavior exhibited by some External fertilization, externally fertilizing species (chiefly amphibians, Amphipoda, amphipods, and horseshoe crabs) in which a male grasps a female with his fro ...

. They can also be used in male–male combat in some species.

Historical background

Austrian biologist

Paul Kammerer Paul Kammerer (17 August 1880, in Vienna – 23 September 1926, in Puchberg am Schneeberg) was an Austrian biologist who studied and advocated Lamarckism, the theory that organisms may pass to their offspring characteristics acquired in their l ...

experimented on

midwife toad Midwife toads are a genus (''Alytes'') of frogs in the family Alytidae (formerly Discoglossidae), and are found in most of Continental Europe and Maghreb, Northwestern Africa. It has also been introduced to Great Britain. Characteristic of these ...

s' nuptial pads. He used the offspring's apparent enlargening from generation-to-generation as evidence of Lamarckian evolution.

Examples

Many

amphibian Amphibians are ectothermic, anamniote, anamniotic, tetrapod, four-limbed vertebrate animals that constitute the class (biology), class Amphibia. In its broadest sense, it is a paraphyletic group encompassing all Tetrapod, tetrapods, but excl ...

species manifest nuptial pads for use in amplexus, an example being the

rough-skinned newt The rough-skinned newt or roughskin newt (''Taricha granulosa'') is a North American newt known for the strong toxin exuded from its skin. Appearance A stocky newt with rounded snout, it ranges from light brown to olive or brownish-black on t ...

, ''Taricha granulosa''.

References

{{reflist, 30em Amphibian anatomy Mating Sexual anatomy

Historical background

Examples

See also

References